A touch display screen used as an input medium is a simplest and most convenient human-computer interaction way, so the touch display screen is increasingly used to a variety of electronic devices. Based on different working principles and a transmission of information media, the touch screen may be classified into four types: an infrared ray touch screen, a capacitive touch screen, a resistive touch screen and a surface acoustic wave touch screen. Since the capacitive touch screen has many advantages, such as a long-term life, a high transmittance and a multi-touch function etc., the capacitive touch screen becomes a mainstream technique of the touch screen. The capacitive touch screen includes a surface capacitive type and a projected capacitive type. The projected capacitive type may be classified into a self-capacitive type and a mutual-capacitive type, wherein the self-capacitive type has a greater touch sensing accuracy and a greater signal-noise-ratio, so the major panel manufacturers favor the self-capacitive type accordingly.
The mutual-capacitive touch screen includes driving electrodes and sensing electrodes formed on a glasses surface. An intersection between the driving electrode and the sensing electrode forms a coupled capacitance, so the driving and sensing electrodes are used as two electrodes of the coupled capacitance. When a finger touches the capacitive screen, a coupling between the two electrodes near a touched point is influenced and the coupled capacitance between the two electrodes is changed accordingly. To detect the mutual-capacitance, the driving electrode outputs an exciting signal and the sensing electrodes receive signals one by one, so the capacitances of the intersections between all of the driving and sensing electrodes can be obtained. That is, a two-dimensional capacitance of the entire touch screen is obtained. According to a variation data of the two-dimensional capacitance of the touch screen, a coordinates of each touch point can be calculated. In an in-cell mutual-capacitive touch screen, the driving electrodes and sensing electrodes in the touch screen structure and metal connecting lines are usually and directly disposed on an array substrate. For example, a common electrode on the array substrate is divided into the driving and sensing electrodes, which extend along directions perpendicular to each other and are isolated from each other. The driving and sensing electrodes are connected to an external driving chip through electrode connecting lines. The diving and sensing electrodes are also used as the common electrode. Therefore, in a display time of one frame, the driving and sensing electrodes time-sharing transmit a common voltage (Vcom) and a touch signal. These signals are provides by the driving chip and the driving chip is a touch and display driver integration (TDDI).
Since the driving and sensing electrodes are formed by dividing the common electrode, they are formed on the same layer structure. In general, the driving electrodes are arranged in laterally-extended strip-shaped structures. The sensing electrode includes multiple sub-electrodes, which are sequentially connected in series by the electrode connecting lines to form a longitudinally-extended electrode structure extending. Therefore, a metal wiring layer including the driving electrode connecting lines and sensing electrode connecting lines is required to be disposed above the common electrode layer relatively. The common voltage and the touch signal transmitted by all of the driving and sensing electrodes are input by the driving chip through the electrode connecting lines. In a display sequence, wiring paths of the driving and sensing electrode connecting lines are different, so a difference of the wiring resistances is larger to result in a larger potential difference between the common voltage of the driving electrode and the common voltage of the sensing electrode. A normal display of a display device is affected accordingly.